Using Yahoo Answers has been on my "to do" ebook marketing list for a while now, but I just tried it for the first time this week. It was actually kind of fun and a little bit addictive.
If you go to http://answers.yahoo.com/ you will get to the main screen. You need to sign in and do a profile.
The site has the questions divided by categories. Choose the category that best fits your ebook. Then view the various questions (there are hundreds each day) and choose those that you can provide a great answer for. It only takes a few minutes for each answer. Leave your website address at the end of each answer. This is just another great way to market your ebook.